The present invention pertains to transporters and methods for transporting individuals, and more particularly to balancing transporters and methods for transporting individuals over ground having a surface that may be irregular.
A wide range of transporters and methods are known for transporting human subjects. Typically, such transporters rely upon static stability, being designed so as to be stable under all foreseen conditions of placement of their ground-contacting members. Thus, for example, the gravity vector acting on the center of gravity of an automobile passes between the points of ground contact of the automobile""s wheels, the suspension keeping all wheels on the ground at all times, and the automobile is thus stable. Another example of a statically stable transporter is the stair-climbing transporter described in U.S. Pat. No. 4,790,548 (Decelles et al.).
In an embodiment of the invention, a transporter is provided for carrying a user. The transporter includes:
a platform which supports a payload including the user,
a ground-contacting module, mounted to the platform, including at least one ground-contacting member, characterized by a ground contact region, and defining a fore-aft plane;
a motorized drive arrangement, coupled to the ground-contacting module; the drive arrangement, ground-contacting module and payload constituting a system being unstable with respect to tipping in at least the fore-aft plane when the motorized drive is not powered, the system characterized by a pitch angle offset from a specified pitch angle and a pitch rate offset from a specified pitch rate; and
a control loop in which the motorized drive arrangement is included, for dynamically maintaining stability of the system in the fore-aft plane by operation of the motorized drive arrangement so that the net torque experienced by the system about the region of contact with the surface causes a specified acceleration of the system, the net torque including a contribution related to the pitch angle offset multiplied by a first gain wherein the first gain is a function of at least one of an orientation and a displacement of the device.
In another embodiment of the invention, a balancing transporter is provided. The transporter is characterized by an instantaneous displacement and orientation. The transporter includes a motorized drive for propelling the transporter; and a control loop in which the motorized drive arrangement is included, for dynamically maintaining stability of the system in the fore-aft plane by operation of the motorized drive arrangement so that the net torque experienced by the system about the region of contact with the surface causes a specified acceleration of the system, the net torque including a contribution functionally related to at least one of the pitch angle, pitch rate, wheel position and wheel velocity, wherein the functional relation varies with at least one of an orientation and a displacement of the device.
In another embodiment of the invention, a method is provided for carrying a payload including a user with a transporter. The method comprises providing a transporter including:
a platform which supports a payload including the user,
a ground-contacting module, mounted to the platform, including at least one ground-contacting member, characterized by a ground contact region and a fore-aft plane;
a motorized drive arrangement, coupled to the ground-contacting module; the drive arrangement, ground-contacting module and payload constituting a system being unstable with respect to tipping in at least the fore-aft plane when the motorized drive is not powered, the system characterized by a pitch angle offset from a specified pitch angle and a pitch rate offset from a specified pitch rate; and causing the motorized drive to operate the ground-contacting module using a control loop in which the motorized drive arrangement is included, for dynamically maintaining stability of the system in the fore-aft plane by operation of the motorized drive arrangement so that the net torque experienced by the system about the region of contact with the surface causes a specified acceleration of the system. The net torque includes
a contribution related to the pitch angle offset multiplied by a first gain K1xe2x80x2 when the pitch angle offset is greater than or equal to zero and to the pitch angle offset multiplied by a second gain K1xe2x80x3 when the pitch angle offset is less than zero; and
a contribution related to the pitch rate offset multiplied by a third gain K2xe2x80x2 when the pitch rate offset is greater than or equal to zero, and to the pitch rate offset multiplied by a fourth gain K2xe2x80x3 when the pitch rate offset is less than zero,
wherein at least one of a first gain pair consisting of K1xe2x80x2 and K1xe2x80x3 and a second gain pair consisting of K2xe2x80x2 and K2xe2x80x3 are unequal.
In a specific embodiment of the preceding embodiment of the invention, the magnitude of K1xe2x80x2 is less than the magnitude of K1xe2x80x3. In a further specific embodiment, K2xe2x80x2 equals K2xe2x80x3.
Embodiments of the invention advantageously allow the response of the transporter to be tailored to rider preferences.